Aeration of slurries



Feb.26, 1935. A. H. HARRISON 1,992,208

AERAT ION OF SLURRI E S Fil'ed Sept. 21, 1933 NVENTOR ARTHUR HUGOHARRISON b ATTORNEY.

I 15 thereon.

.PatentedFeb. 26, l935 1. v 1 p v v ntario, Canac laj Applicationseptember'zifisas, Serial No. 90.340 4 Claims (C l.83" 73)" V Thisinvention relatesto the aerationofslurries or the like for carrying the*aerated slurry to the in the. production of porousbuilding materials;point of further processing. Within the chamber It is applicable tocementiti'ousmaterials, which 16 a plurality of bubble-slicing blades 19are 'ar-' have the: inherent capacity to "set and harden ranged jfor-rotation-upon ashaft20 and alwallupon hydration,'and equally well tomaterials, cleaning device, or scraper 21" is similarly arwhich have notin themselves this settingcapacranged. The blades 19 have a stream-lineconity but: which require some further processing touras illustrated toprovide for self-cleaning step to bind the aerated mass into permanentthereof. r N form, such; for example, as lime and clay, which Inoperation a Slurry, Comprising mixture may be hardened bycarbonation andburning of water and cement,pla ster of Paris, lime, .c1ay j10respectively. 7 01' the like, and containing any suitable ,bubble In myapplication for patent, No. 620,845, I forming agent, is fed into thechamber lby means have disclosed a method of aerating slurries and 0fthe p p 6 a a at a desired elw ich the present invention is a furtherimprovement may vary from atmospheric up, is admitted at 12. f Air inexcess of that to be incorporated in the The invention will be describedwith reference slurry is maintained in the aerating chamber and to theaccompanying drawing, in which-- the pressure within the chamber ismaintained H Figure l is a side elevation, partly in section, constantwhile producing a cellular product of a of a suitable apparatus foraerating slurries in given weight. The extent of this" pressuredeteraccordance with the invention, and mines the-weight of the aeratedproduct. 'lEtota- 2O Figure 2 is a cross sectional viewoi a portion tionof thejblades 3 incorporates the air in the of the apparatus. I slurry,where it is retained by the bubble-form- In the drawing, 1 represent achamber providing agent; i The period of agitation and the rate ing theclosed space within which the aeration at which the shafts 2 travel willinfluence the of the slurry is eifected. Rotatable shafts 2 carry amountof air incorporated in the slurry but in 25 a plurality of agitatorblades 3, the ends of which Fpractice these factors are preferably fixedat .the are bentat right angles along the wall of the most convenientpoint and the extent of aeration chamber to provide scrapers for keepingthe is governed by the" pressure maintained on the walls clean and freefrom accumulations of matepredetermined volume of air in the chamber.In-

'30 rial which, in some cases, might have a tendency crease in pressureincreases the amount of air to set and harden thereon. The agitatorblades occluded in the slurry and when the aerated slurry have astream-line contour to prevent accumuis discharged through thepump 8 themass ex- Q .lations thereon. The shafts 2 are mounted in any pands withfreedom from super-atmospheric pressuitable bearings. Agear wheel 4 onthedriven. sure. I

shaft meshes with a similar gear on the other Substantial pressures arefrequently employed 35 shaft and is driven at the desired rate by anyand in accordance with the invention the aerated suitable means, notshown. Slurry is fed into one slurryis discharged into thebubble-slicing chamend of the chamber through the inlet5 by means ber 16and furtherv agitated, under atmospheric of a pressure-sustaining pump 6and is discharged pressure, to subdivide the expanded bubbles into 10therefrom by a similar pump 8 and outlet 7. The smaller units in orderto avoid loss of air, with pumps 6 and 8 are actuated by means of theshafts the consequent. increase in weight, and, at the 9 and 10,respectively, which may be driven by any, same time, to uniformlydistribute the bubbles suitable means, not shown. Impellers, 11, tendingof substantiallyuniform and smaller size within L to accelerate thetravel of the slurry in the chamthe mass. The level of the slurry in thechamber j bar, may be provided on the agitator blades ad- .16 is alwaysmaintained substantially above the 45 jacent thefeed end, middle anddischarge end top slicing bladel inordertoavoi'd the introof the chamberor all blades may be so equipped. duction of additional air from theatmosphere to Air under pressure is admitted a A Dreswhichthe surface ofthe mass is exposed. It will Y sure reducing valve 13 is provided formaintain bea'p'preciated that when the aerated mass is lib- ,ing apredetermined constant pressure within the erated from a pressure of,say, or pounds 50 chamber, as well as a cock 14 and a pressure persquare inch, the cells may expand sosuba e i r stantially that some ofthe cells break, allowing The outlet 7 preferably discharges intoan openair to escape and leaving the mass unevenly agitating or bubble-slicingchamber 16 having a aerated, while the cells may beyundulylarge for 66discharge outlet 17 leading to a conveyor belt 18 some uses to which theaerated slurry is put;

The i e-agitation of the slurry under normal atmospheric pressura'asdescribed overcomes these illustrative may be mentioned rosin soap; glueand saponin which may be used alone or in com-l binationr I I claim: V r

1. A method of aeratingslurry which comprises agitating a slurrycontaining a bubble forming' agent in the presence of a predeterminedvolume-. of air maintained under a constant pressure inexcess. ofatmospheric to incorporate air in the slurry;reducing;thepressuretothatoftheatmos- 7 4 phere anda re-agitatingthevexpanded: cellular massw". V .7

2'. In the production of cellular building materials, the continuousmethod of aerating a slurry containing a bubble-forming agent, whichcomprises continuously feeding the slurry into a chamber in which ismaintained'a predetermined volume of air under super-atmosphericpressure;

agitating the slurry to incorporate air therein, reducing the pressureon the aeratedslurry and re-agitating the expanded mass to subdivide thecells therein.

3. Apparatus for aerating'slurry which com prises an aeratingchamber,means for maintaining a predetermined volume of air in said chamberunder super-atmospheric pressure, means for continuously feeding slurryto said chamber a. adapted to maintain said super-atmospheric pressuretherein, similar means for continuously discharging the aerated slurryfrom said chamber and means in-said chamber for incorporating air in theslurry.

4. Apparatus as defined n claim 3 having in/ combination withsaiddischarge" means a bubbleslicing chamber for re-agitating'the aeratedslurry under; atmospheric pressure.

A THURL UGOHAR ISON.

